Search Results

This investigation evaluates the energy consumption of an electric vehicle (EV) and identifies key factors that affect its energy efficiency, based on real-world operation for a range of driving characteristics and climate conditions over nearly four years in the streets of the second-largest UK city. The driving modes investigated were acceleration, deceleration, idling and cruise, determined by dividing each individual trip into kinematic segments based on vehicle speed and acceleration calculated second by second. From the results obtained, the EV energy consumption is directly influenced by changes in ambient temperature outside, largely due to the corresponding loads required from the use of auxiliary systems, mainly heating and air conditioning. An increase in trip idling events directly translates to a rise in EV energy consumption, while opposite outcomes were produced during cruising state with decreasing energy consumption.

In Brazil, since the purchase cost of an electric vehicle (EV) is still very high, the exchange of a conventional vehicle by an EV would only be worth if the vehicle was used as source income, such as the case of taxis. Short run distances and high daily mileage make conventional taxis ideal candidates to be replaced by battery EVs. Recently, São Paulo and Rio de Janeiro received EVs as a test project, but other major cities, such as Belo Horizonte, have yet to be tested. The taxi fleet in this city has currently 7,152 vehicles, all powered by internal combustion engines, significantly contributing to equivalent carbon dioxide (CO2eq) emissions since the daily distance traveled is high. With the aim to characterize the fleet and evaluate taxi driver’s option to EVs, data was collected from a systematic sample of taxi stands, of a total of 375, through a structured interview with the drivers, considering a finite and homogeneous population.

The demand for optimization of engine design and operating conditions in order to achieve fuel economy and attend strict emission legislation leads to development of engine simulation tools. The virtual testing tools provide results in a short time with low costs, and enable larger variation on the design and operational conditions. Nowadays engine simulation is performed by commercial software or open source models. In one hand, commercial software are able to simulate complex quasi or multi-dimensional models and have an intuitive interface with the user. The model validation can be extremely difficult since specific model details are not known. In the other hand, the open source models are appropriate for thermodynamic models capable of predicting in-cylinder data and pollutant emissions. The validation process in this type of tool is usually simple since all assumptions of modeling are known.

This paper presents the physical adjustments and the incorporation of a control system to injection, ignition and throttle valve parameters for operation of a diesel engine with 100% hydrous ethanol. The control system of the aforementioned parameters integrates three dependent subsystems. The control systems of the throttle valve opening, fuel injection and ignition timings have the purpose to reduce cylinder pressure, control engine speed and the combustion process. The signals generated depend on engine speed and knock sensors, which are operated by microcontrollers programmed in Assembly and C language. The measured parameters during engine operation are relative humidity, temperature in different engine locations, fuel consumption and intake air mass flow rate. The data collected are monitored by a software developed in LabVIEW platform. The software also controls the load applied at each engine operating condition.

This study presents the effects of fuel blends containing 5%, 10%, 15% and 20% of anhydrous ethanol in diesel oil with 20% of biodiesel (B20) on performance, emissions and combustion characteristics of a diesel engine. The engine was tested with its original configuration and in the lower brake specific consumption region, at 1800 RPM. The results showed that in-cylinder peak pressure and heat release rate increased with the use of ethanol. The use of ethanol increased ignition delay and decreased exhaust gas temperature. Brake specific fuel consumption increased with ethanol addition, and fuel conversion efficiency was not affected. Increasing ethanol content in the fuel caused decreased carbon dioxide (CO2), carbon monoxide (CO) and total hydrocarbons (THC) emissions.

In a scenario with growing population, increasing demand for energy and volatile prices of fossil fuel, there is a high incentive for the use of biofuels, especially those produced from waste material. In this context, second and third generation bioethanol (2G/3G) are interesting alternatives, as they can be produced from different raw material such as corn and rice straw, sugarcane bagasse, waste from pulp industry and microalgae. This paper presents an overview of the available technologies for both 2G and 3G bioethanol production, including lignocellulosic biomass feedstock, biocatalysts and cogeneration processes.

The solubility of ethanol in diesel oil with biodiesel is a limiting factor for its use as fuel for compression ignition engines. The stability of blends of ethanol with concentration varying from 5% to 30% in diesel oil containing 7% of biodiesel (B7) was evaluated at temperatures from 16°C to 25°C. The blends were conditioned in graduated glass cylinders and kept at the test temperatures, being observed the blend phase separation percentage in specific time schedules. The results show the stability time of each blend, indicating the maximum storage and use periods for the ethanol concentration evaluated. The results demonstrate that fuel blends with ethanol concentrations up to 15% can safely be used as engine fuels, as far as the tested parameters are concerned.

This work evaluates the impacts on the temperature and flow fields caused by alteration on the geometry of an automotive engine cooling water pipe section. The pipe section studied is located after the water pump. The straight pipe section was altered to a curved section and it was located closer to the exhaust pipe, to attend engine downsizing demands. The analysis was carried out though the finite volume method, considering steady-state, bi-dimensional flow. The results point out that pressure drop in the conduit is little altered with geometric variations, but the temperature conditions are affected by the proximity of the duct to the heat source.

This paper presents an investigation on fuel consumption of a diesel engine fuelled with blends of natural gas-diesel and hydrogen-diesel. Experiments have been carried out in a 50 kW, four-stroke, diesel engine. Natural gas and hydrogen have both been injected in the intake manifold, while diesel was directly injected in the combustion chamber. Blends of 25%, 50% and 75% of natural gas in diesel were tested, while the concentrations of hydrogen were 20%, 30% and 50%. No alteration in the diesel injection system has been made when the gaseous fuels were used. The results show that diesel consumption is reduced proportionally to the necessary air amount for stoichiometric burn of the gaseous fuels.

This work describes an updated cold start system for ethanol fuelled engines using an electronic gasoline injector. The new system is a substitute to the conventional cold start system that employs a calibrated hole for gasoline introduction in the intake pipe. The new system is constituted by a gasoline reservoir, electrical fuel pump, fuel injector, fuel filter, and solenoid valve frequency controller. Experiments have been carried out in a production 1.0-liter, four-cylinder, ethanol-fuelled engine, submitted to transient emissions tests after cold start. The results show that the updated system reduces the cold start period by 31% in comparison to the conventional system. Acceleration after cold start was also improved, with gasoline consumption reduction of 67%.

Along the last thirty years one of the challenges is to develop an engine working with ethanol with the same performance and characteristics of gasoline engines functioning at low temperatures. In Brazil the production expansion of flex fuel engines is the main motivation for technology development and research to improve the engine cold start and functioning, when using ethanol. The use of gasoline as an auxiliary in the cold start system is now the main characteristic of this system. In this work the performance of a new cold start system is analyzed. Tests were performed in a vehicle and the results show the potential of the new technology.

The increasing number of flex fuel vehicles using pure or mainly ethanol when mixed with gasoline led to a necessity of an auxiliary cold start system. These systems are based on introducing gasoline during the engine's cold phase. The researches lead to find an alternative to avoid using gasoline at cold start systems. This works presents a numerical analysis of the flow and heat transfer in a cold start system, using computational fluid dynamics. A prototypal vehicle was used to validate the simulations. The tests were done at controlled ambient temperatures: 0°C for cold start measurements and 25°C at chassis dynamometer to run the FTP75 emission cycle. The numerical data were validated and the results showed the possibility to get a temperature high enough to assure fuel combustion with emissions benefits.

The use of pure ethanol or the prevailing of it in the mixture with gasoline in flex fuel engines, led to a necessity of an auxiliary system to the cold start and engine functioning. Ethanol chemical properties can be used to explain this necessity. Ethanol is been used in Brazil for more than 30 years and many researches give support to the cold start technologic evolution. The cold start system enables the gasoline introduction into the intake manifold of flex fuel engines, when vehicles are using pure ethanol or a mixture with more ethanol than gasoline. The researches challenge is to find a way to start an engine using ethanol without the use of the cold start system using gasoline. This works presents a numerical analysis of the flow and heat transfer in a cold start system, using computational fluid dynamics. An experimental test bench developed to study a start cold system heating air and ethanol.

Cold start systems provide the introduction of gasoline inside the engine intake system during cold start and warm-up acceleration, as ethanol fuel shows engine operation difficulties at low temperatures. Despite the technological evolution, traditional cold start systems may present problems mainly related to flow control and gasoline distribution to the engine cylinders hindering cold start and warm-up operation with the increasing of emissions levels and fuel consumption. The cold start system used allows for simultaneous gasoline introduction through calibrated orifices in the four conduits of the intake system. Adjustment of gasoline flow is made by an electronic fuel injector. The objective of this work is to analyze numerically and experimentally the gasoline flow in an auxiliary cold start system for vehicles with engines using ethanol or ethanol-gasoline blends (flex fuel).

Current ambient and technological demands on automotive emissions and oil consumption motivate the development of basic lubricant oils of high thermal and chemical stability and use of highly specified additives. This work evaluates some types of friction modifier additives present in spark ignition and compression ignition engine oils, using a four-balls measuring device. The tribology of conventional lubricating oils were evaluated and compared to those of lubricating oils with friction modifier agents. The test results allowed for determination of the effects of utilization of friction modifiers in automotive lubricating oils.

The intake valves of a 1.0 liter, 16-valve production engine has been phase shifted to increase the intake air charge, aiming at improved performance. The engine has been tested in a dynamometer bench to verify the performance attained with the modification and its influence on raw exhaust emissions. Total hydrocarbons, carbon monoxide, nitric oxide and oxides of nitrogen emissions were analyzed for varying load and engine speed. The results have shown that shifting the valves of a dual intake valves engine can provide increased performance, while keeping emissions at acceptable levels.

The piston and intake valves alternate movements produce pressure waves that propagate throughout the intake conduit. Such waves can adequately increase the intake air mass charge to the engine cylinders. In the present work an experimental study on the engine intake valves phase shift was carried out with the objective to analyze its influence on the intake air mass charge. A production 1.0-liter, 16-valve engine was used, with two intake valves per cylinder. Preliminary tests were conducted in a flow bench, simulating the engine intake air flow conditions, and, then, the engine was tested in a dynamometer bench. The results in the flow bench showed that the intake air mass charge is increased up to a phase shift angle of about 30 degrees. From the tests conducted in the dynamometer tests, results are shown for a phase shift angle of 7.5 degrees, with one of the intake valves opening late with respect to the original opening angle.

This work presents an optimized model that calculates the rate of formation of oxides of nitrogen in spark-ignited internal combustion engines. Model optimization was done by establishment of a correlation between the fuel-air mixture equivalence ratio and the first rate reaction constant of the Zeldovich's mechanism, which describes the kinetics of formation of nitric oxide. The calculated values by the model were compared to experimental data available from a single-cylinder engine, featuring a disc type combustion chamber, for variations of fuel-air mixture equivalence ratio. When the mixture equivalence ratio was varied, the optimized model produced calculated values much closer to the experimental results than the previous model, especially in the lean mixture region and in the peak region near to stoichiometry.

This work has as an objective the development of a numerical model to calculate the kinetic formation rate of carbon monoxide in spark-ignited internal combustion engines. The model is added to a computer program that simulates the cycle of spark ignition engines, to calculate the exhaust concentration of carbon monoxide emissions. The model is validated through experimental data from a single-cylinder research engine. Comparisons with calculated equilibrium concentration of carbon monoxide confirm that this pollutant should be modeled according to the theory of kinetic formation, for a better approach to exhaust measured values.

Four samples of three different types of gasoline found in Brazil were tested to verify their aging effects on engine performance and exhaust emissions: two samples of regular gasoline, one sample of regular gasoline plus additives, and one sample of premium gasoline. The regular gasoline is the most commonly used automotive fuel in Brazil; regular plus additives contains an improved detergent capacity; and premium is a gasoline of higher octane number. All these types of gasoline are, in fact, a blend of approximately 75% gasoline and 25% ethanol, with the ethanol having an anti-knocking function. The gasoline samples were tested in a total period of six months, using a production 1.3-liter, four-cylinder, sixteen-valve engine mounted on a bench test dynamometer. Performance parameters and exhaust emissions levels were obtained for engine speeds of 1000 to 6000 rev/min. The general test results point to an increase in HC and CO emissions and in fuel consumption with fuel aging.